Dynamically reconfiguring time zones in real-time using plural time zone libraries

ABSTRACT

A computer program product for dynamically reconfiguring time zones in real-time using plural time zone (TZ) libraries is provided. The method provides integrating a first time zone information data (TZID) version and a second TZID version into a TZ library in an operating system. A first configuration comprising the TZ library and the first TZID version is selected. Responsive to adjusting the first configuration to a second configuration comprising the TZ library and the second TZID version, the second configuration is used automatically without restarting the operating system and without restarting an application.

FIELD OF THE INVENTION

This disclosure relates generally to management of pre-defined time zonedefinitions, and more particularly to dynamically reconfiguring timezones in real-time using plural time zone libraries.

BACKGROUND

Modern operating systems may support multiple independent time zone (TZ)libraries, such as Olson and POSIX, which are collections of TZinformation data by time zone. The TZ libraries and associated TZinformation data may be provided as a series of data files. Each TZlibrary may be searched to obtain the desired TZ information data for agiven time zone, for example an offset from Universal Standard Time(UTC), and any applicable Daylight Savings Time (DST) rules.

A computer system may provide a default system-wide TZ library/TZinformation data pair setting. Additionally, each user, or application,may have a customizable profile where a preferred TZ library/TZinformation data pair is set that overrides the system default.Therefore, within the same computer system several different TZlibrary/TZ information data pair settings may exist. A system-providedapplication programming interface (API), for example the localtime( )function, checks system TZ setting, accepts as input a TZ library/TZinformation data pair and returns the time for the requested time zone,formatted according to language and locale settings associated with therequested time zone. However, the TZ library/TZ information data pair isfixed for the duration of the application or user session, and may notbe changed dynamically.

Regions around the world can change their TZ information data, forexample DST rules, at any time, thereby requiring an update to TZlibraries and TZ information data many times throughout the year to staycurrent with all the latest TZ information data changes worldwide.However, because updates to TZ information data may be supplied as partof a vendor's operating system maintenance, where the customer'soperating system may be not regularly maintained and updated, the TZinformation may not be consistent across versions of TZ information dataand between TZ libraries. As a result, when TZ information data for a TZlibrary becomes out of date, the inaccurate time data may adverselyaffect applications while the users wait for the operating system vendorto supply an update.

SUMMARY

According to one embodiment, a method dynamically reconfiguring timezones in real-time using a plurality time zone libraries comprises:integrating a first time zone information data (TZID) version and asecond TZID version into a TZ library in an operating system; selectinga first configuration, wherein the first configuration includes the TZlibrary and the first TZID version; and responsive to adjusting thefirst configuration to a second configuration, utilizing the secondconfiguration, wherein the second configuration includes the TZ libraryand the second TZID version, and wherein the second configuration isutilized automatically without restarting the operating system or anapplication.

According to another embodiment, a computer program product fordynamically reconfiguring time zones in real-time using a plurality oftime zone libraries comprises: a computer readable storage mediumreadable by a processing circuit and storing instructions for executionby the processing circuit for performing method comprising: integratinga first time zone information data (TZID) version and a second TZIDversion into a TZ library in an operating system; selecting a firstconfiguration, wherein the first configuration includes the TZ libraryand the first TZID version; and responsive to adjusting the firstconfiguration to a second configuration, utilizing the secondconfiguration, wherein the second configuration includes the TZ libraryand the second TZID version, and wherein the second configuration isutilized automatically without restarting the operating system or anapplication.

According to another embodiment, a computer system for dynamicallyreconfiguring time zones in real-time using a plurality of time zonelibraries comprising a memory, a processing unit communicatively coupledto the memory, and a management module communicatively coupled to thememory and processing unit, wherein the management module is configuredto perform the steps of a method comprising: integrating a first timezone information data (TZID) version and a second TZID version into a TZlibrary in an operating system; selecting a first configuration, whereinthe first configuration includes the TZ library and the first TZIDversion; and responsive to adjusting the first configuration to a secondconfiguration, utilizing the second configuration, wherein the secondconfiguration includes the TZ library and the second TZID version, andwherein the second configuration is utilized automatically withoutrestarting the operating system or an application.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in conjunction with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 illustrates an exemplary computer system environment operable forvarious embodiments of the disclosure;

FIG. 1A illustrates components and algorithms associated with managingplural time zone libraries, according to various embodiments of thedisclosure;

FIG. 1B illustrates components associated with time zone version data,according to various embodiments of the disclosure;

FIG. 2 is an operational flow chart of an exemplary embodiment of thedisclosure; and

FIG. 3 is a schematic block diagram of hardware and software of thecomputer environment according to an embodiment of the process of FIG.2.

DETAILED DESCRIPTION

Although an illustrative implementation of one or more embodiments isprovided below, the disclosed systems and/or methods may be implementedusing any number of techniques. This disclosure should in no way belimited to the illustrative implementations, drawings, and techniquesillustrated below, including the exemplary designs and implementationsillustrated and described herein, but may be modified within the scopeof the appended claims along with their full scope of equivalents.

The present disclosure relates generally to the field of managing pluraltime zone libraries, and more particularly to time zone reconfigurationin real time. The following described exemplary embodiments provide asystem, method and program product to provide an enhanced applicationprogram interface (API), such that multiple versions of time zone (TZ)information data may be dynamically selected, in real-time, for a TZlibrary.

As will be appreciated by one skilled in the art, aspects of the presentdisclosure may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present disclosure may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit”, “module”, or “system”.Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Aspects of the present disclosure are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus,(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions.

Turning now to FIG. 1 a block diagram of an exemplary data processingsystem operable for various embodiments of the disclosure is presented.In this illustrative example, the data processing system 100 includes aserver 102 providing enhanced TZ management 109. The server 102 may beconnected to other computers and servers via a network 130. The network130 may include connections, such as wire, wireless communication links,or fiber optic cables.

The server 102 includes a processor unit 104 that executes instructionsfor software, for example the operating system (OS) 108 and TZmanagement 109 (discussed in further detail with respect to FIGS. 1A and1B) that may be loaded into memory 106. The processor unit 104 may be aset of one or more processors or may be a multi-processor core,depending on the particular implementation. Further, the processor unit104 is connected, via a bus 120, to memory 106, a network interfacedevice 118, disk storage 121, persistent storage 116, and input device122, and an output device 124.

The server 102 is generally under the control of an OS 108, for exampleLinux. However, any operating system supporting the functions disclosedherein may be used. The processor 104 is included to be representativeof a single CPU, multiple CPUs, a single CPU having multiple processingcores, and the like. Similarly, the memory 106 may be a random accessmemory. While the memory 106 is shown as a single identity, it should beunderstood that the memory 106 may comprise a plurality of modules, andthat the memory 106 may exist at multiple levels, from high speedregisters and caches to lower speed but larger formats. The networkinterface device 118 may be any type of network communications deviceallowing the server 102 to communicate with other computers, includingthe client 125, via a network 130.

Persistent storage 116 is any device or hardware that is capable ofstoring information, such as, data, an OS 108, and program instructions,including those providing TZ management 109. Persistent storage 116 maytake various forms depending on the particular implementation. Forexample, persistent storage 116 may be disk storage 121, a flash memory,optical disk, magnetic tape, cloud storage devices, or some combinationof the above.

Instructions for the OS 108, TZ management 109, applications and/orprograms may be located in persistent storage 116, which is incommunication with processor unit 104 through the bus 120 fabric. Inthese illustrative examples the instructions are in a functional form onpersistent storage 116. These instructions may be loaded into memory 106for execution by processor unit 104.

The input device 122 may be any device for providing input to the server102. For example, a keyboard and/or a mouse may be used. The outputdevice 124 may be any device for providing output to a user of theserver 102. Although shown separately from the input device 122, theoutput device 124 and input device 122 may be combined, as in a displayscreen with an integrated touch-screen.

As will be discussed with reference to FIG. 3, the server 102 and thecomputer hosting the client 125 may include internal components 800 andexternal components 900.

FIG. 1A further illustrates the components and algorithms associatedwith TZ management 109 running on the server 102, according to at leastone embodiment of the disclosure. As used herein, time zone management109 (FIGS. 1, 1A) includes functionality that the operating systemperforms on behalf of time management 109 (FIGS. 1, 1A), such asretrieving environment variables, and reading files.

A TZ reconfiguration algorithm 110, illustrated and explained in furtherdetail with respect to FIG. 2, takes as input the time zone library(TZL) rules of reconfiguration 111 and the TZ name retrieval policy 114to determine which of the TZ libraries 113 should be used to reconfigurethe time settings on a computer. Time zone management 109 is shown anddescribed through an algorithm, configuration rules, and components thatare specialized for performing TZ information data and TZ library 113management. However, those skilled in the computer arts will appreciatethat time zone management 109 may be embodied in components andreconfiguration rules other than those described.

A TZ library is a compilation of information about the world's timezones that is primarily intended for use with computer operating systemsand software programs. In the well-known Olson based TZ libraryimplementation, data is organized by a unique name, referred to as a TZname. The TZ name denotes a geographical location in the form ofArea/Location, for example, America/New_York. Data that is associatedwith a TZ name includes an offset from Greenwich Mean Time (GMT),commonly referred to as Coordinated Universal Time (UTC), and theprecise moment that local time transitions as one moves from one timezone to another. Each Area/Location entry and its associated data in aTZ library 113 may also be referred to as a TZ rule. For example, fortime zones that observe daylight savings time (DST), the TZ rulespecifies the precise dates and times of the transition to and from DST.Entries for an Area/Location may include rules that contain time zonedata modifications for future dates, as well as historical data fromprior decades.

Two other well-known time zone data formats are the Portable OperatingSystem Interchange (POSIX) and International Components for Unicode forC and C++ (ICU4C). An exemplary TZ name in POSIX may take the form stdoffset dst (spaces added for readability), where std is a string thatspecifies the name of the time zone, offset is a value that when addedto local time gives a UTC time value, and dst specifies a string thatspecifies the name of the time zone if DST is observed. In POSIX format,for example, America/New_York may be indicated as EST5EDT. ICU4Cprovides an Olson based TZ library implementation that is optimized forUnicode. The Unicode standard provides a universal character set fortext, thus enabling the processing, storage and display of text in manylanguages.

The Olson, POSIX, and ICU4C libraries, and the international standardsto which they conform, are maintained by the different organizationsthat provide them. An operating system vendor receives the TZ librarydata from each of the providers and incorporates each TZ library 113into the operating system in platform-dependent binary format. There maynot be a coordinated update schedule among the different TZ libraryproviders for supplying updated TZ library data. Therefore, if a userhas an urgent need, such as to repair an error in the TZ rules, or if alocation changes its TZ rules, an updated TZ library 113 may not bedelivered in a timely manner to coincide with the operating systemvendor's maintenance release. As a resolution, the operating systemvendor may periodically provide updates to the TZ library 113 in timezone information data (TZID) versions 112. A TZID version 112 maycontain a series of files, for example, one for each TZ name (i.e.,Area/Location) or only for a particular Area. With this architecture,the operating system vendor may be able to respond more quickly to acustomer's request for maintenance, since only the TZ data for theaffected area, for example, for America/Argentina/San_Luis needs to beprovided, even if TZ library data is not yet available for other Areasand Locations. Since the granularity of the TZ data is localized toAmerica/Argentina/San_Luis, customers in other time zones may decide notto install this update without negatively impacting the operation oftheir computers and applications.

In addition to the well-known TZ libraries 113, a user may customize aTZ library 113 for the requirements of the user's location and computersystem. For example, a given geography (e.g., a region, city, time zone,etc.) may now be required to observe DST, where before only standardtime was observed. As previously described, a TZID version 112containing the new TZ rules for the geography needing the change may notbe available in time for the geography to begin observing DST. Withoutan updated TZ library 113, the computer's operating system can onlyreflect the now-outdated TZ rules to applications requesting the localtime and date. In this case, the system administrator may create acustomized TZ library 113 for use, for example, until the new updated TZrules are incorporated in a new TZID version 112 for one of the main TZlibraries 113. Alternatively, the system administrator may prefer tomodify and use this customized TZ library 113 instead. An operatingsystem vendor may provide a set of software utilities to facilitate thesystem administrator's creating a customized TZ library 113.

The TZL rules of reconfiguration 111 represent a set of pre-definedvariables and associated system logic through which a user customizesthe interaction with an application or operating system. The TZL rulesof reconfiguration 111 also provide guidance to the operating system,such as defining a priority order for choosing TZ libraries 113, anddefining the location, i.e., path, where the TZ libraries 113 arestored. The pre-defined variables include LANG, which sets the system'sdefault locale, i.e., language, territory, and code set combinationsused to identify a set of language conventions, and LC_TIME, whichdetermines the locale for date and time formatting. The TZ environmentvariable contributes to setting the TZ rules for the operating system.The format of the value of the TZ environment variable may vary,depending upon the particular system implementation. In that case,system logic may determine, for example, which TZ library 113 should beaccessed to set the TZ rules. The TZL rules of reconfiguration 111 maypredefine default settings for all users on a system-wide basis.However, the system-wide defaults may be overwritten by setting one ormore of the environment variables in the profile of an application oruser.

The TZ name retrieval policy 114 consists of a set of conventions thatare input to the TZ name retriever 115 for exploring a best fit for a TZname. The TZ name retrieval policy 114 is a platform dependent policythat may be modified by a user, using for example a command line,graphical user interface (GUI), program code, or other similar interfaceprovided for the purpose.

The TZ name retriever 115, applies the TZ name retrieval policy 114 andthe TZL rules of reconfiguration 111 to determine a TZ name and TZlibrary 113 to search for the appropriate TZ rules for the customer'sinstallation. For example, a TZ environment variable setting in the formof Area/Location may suggest to the TZ name retriever 115 that a TZlibrary 113 having an Olson format should be searched. Similarly, a TZenvironment variable in the form of std offset dst (spaces added forreadability) may indicate that a POSIX format TZ library 113 should besearched. According to the TZ name retrieval policy 114, the TZ nameretriever 115 may search any other available list of TZ libraries 113and TZID versions 112, in addition to the current list pointed to by theTZ name retrieval policy 114. For example, if the TZ name retriever 115does not find the expected TZ name, the TZ name retriever 115 may searchin another available TZ library 113 and related TZID versions 112. Ifthe expanded search fails, the TZ name retriever 115 may use the defaultUTC format instead.

The TZ version checker 117 compares TZID versions 112 and maintains theuser-defined search order for TZ libraries 113 and the TZID versions 112within the TZ libraries 113. In one embodiment, as part of a system-wideconfiguration task, for example, user, typically the systemadministrator, may dynamically re-arrange the order the TZ versionchecker 117 uses to search the TZ libraries 113 and TZID versions 112within them. A system-wide TZ reconfiguration may require a reboot ofthe operating system, since the major operating system processes requirean orderly stop and restart to activate the changes. However, the TZversion checker 117 sets the default TZL pointer 134 (FIG. 1B),according to the user's selection, thereby allowing the user todynamically perform a system-wide TZ reconfiguration without theaforementioned disruptions. In practice, for example, the user mayinvoke a configuration graphical user interface (GUI) displaying theavailable TZID versions 112. The user may define a search order thatspecifies that the most current TZID version 112 should be the first inthe search order only for applications in the test environment. The TZversion checker 117 and the default TZL pointer 134 (FIG. 1B) allow theuser to dynamically re-arrange, i.e., update, the search order as-neededuntil sufficient testing is completed. The user may then alter thesearch order and promote the most current TZID version 112 to first inthe search order in the production environment. As the user orders andalters the search order for TZ libraries 113 and TZID versions 112, theTZ version checker 117 is invoked to maintain the user's search order.TZ version checker 117 may maintain the user-defined search order as anordered list, such as a linked list, ordered by timestamps, versionnumbers, a date associated with a TZID version 112, a patch identifier,or other similar factors. In another embodiment, assuming properauthorization, an individual user (i.e., not a systems administrator)may similarly perform TZ reconfiguration for a particular application orgroup of users for which the user has support responsibility. In thiscase, system security settings may limit the scope of permissiblechanges to only those specific to the profiles defined for theapplication or users.

FIG. 1B further illustrates the components (previously discussed in FIG.1A) associated with TZ information data within TZ management 109 (FIGS.1, 1A). The TZL rules of reconfiguration 111 represent variables thatcustomize the interaction of a user or application with the operatingsystem. The TZL rules of reconfiguration 111 are shown as a number offiles, each representing the customization settings for a user,application, or the system default profile. The TZL rules ofreconfiguration 111 provide guidance to the TZ name retriever 115 (FIGS.1, 1A) and the operating system in locating the required TZ library 113and TZID version 112. For each of the TZ libraries 113, there may be oneor multiple TZID versions 112, collected into a TZID version library 112a. Each of the TZID versions 112 shown represents a maintenance updateto the TZ library 113. Here, the Olson library is associated with theTZID versions 112: v2012a; v2012j; v2013a; and v2013b. The various TZIDversions 112 within the TZID version library 112 a may be files, tables,arrays, lists, or other organization schemes suitable for the purpose ofsearching and retrieving data collections.

As shown, the default TZL pointer 134 indicates that the Olson libraryis the default TZ library 113 and version v2013b is the default TZIDversion 112, resulting in the default pairing of Olson and v2013b. TheTZL pointer 134, is set based on the user-defined search order, asmaintained by the TZ version checker 117 (FIGS. 1, 1A). However, a usermay require a TZ rule that is not contained within the default version,v2013b. As described with reference to the TZ version checker 117 inFIG. 1A, the user may dynamically select another TZID version 112 withinthe TZ library 113. Alternatively, the user may choose to view other TZlibraries 113 and their corresponding lists of TZID versions 112.

When a vendor provides maintenance updates to an operating system,updates to the various TZ libraries 113, here indicated as 132, may beprovided as part of the maintenance as well. A platform-dependent TZupdate process 130 installs the various TZ library updates 132 to alocation where TZ management 109 (FIG. 1, 1A) or other processes of anoperating system, may access them. The various user-defined and defaultsearch orders may be updated according to the TZ name retrieval policy114.

FIG. 2 describes an exemplary embodiment of the TZ reconfigurationalgorithm 110 (FIG. 1, 1A). The TZ reconfiguration algorithm 110 (FIG.1, 1A) is a process for managing plural time libraries for time zonereconfiguration in real-time. In some implementations, a user makes a TZreconfiguration while logged into the computer within a shell. A shellis a system-supplied interface through which the user enters commandsand otherwise interacts with the operating system. For the TZreconfiguration to take effect, the user may be required to log off andestablish a new shell environment, which will now contain any updatedenvironment variables, such as the TZ environment variable representingthe user's desired time zone. A system-wide TZ reconfiguration mayrequire a reboot of the operating system, since the major operatingsystem processes require an orderly stop and restart. The exemplaryembodiment of the present invention, described in FIG. 2, allows theuser to dynamically perform TZ reconfiguration without theaforementioned disruptions.

At 210 a user or application program requests the computer's local timeusing a computer-provided interface. For example, an application programmay invoke the localtime( ) system library subroutine or a user mayissue the date shell command. Local time is derived from the computer'ssystem time. System time is measured by the system clock, whichtypically counts the number of ticks since some arbitrary starting date.System library subroutines and commands convert the system time to ahuman-readable format, applying any localization and time zone settingsas part of the conversion.

Upon receiving a request to format local time, at 215 time zonemanagement 109 (FIGS. 1, 1A) checks to see if a TZ library 113 isspecified in the request. If so, time zone management 109 searches thepre-defined variables of the TZL rules of reconfiguration 111 (FIGS. 1,1A) for a setting corresponding to a desired TZ library format, such asOlson. An operating system maintains a set of variables, typicallyreferred to as a default profile, that define the operating environment.Each user and application may have an individualized profile containingits own variable settings. Where a variable is defined, that setting mayoverride the corresponding setting in the default profile. However,where a variable is not present, then the user or application profileinherits the variable and its setting from the default profile.

If at 220 a setting corresponding to a TZ library 113 is located withinthe TZL rules of reconfiguration 111 (FIGS. 1, 1A), then the specifiedTZ library 113 is loaded. However, if at 225 a variable is not set toindicate the desired TZ library 113, or if, for example, the desired TZlibrary 113 cannot be found, another TZ library 113, for example, the TZlibrary 113 setting from the system default profile is used.Subsequently, a component of TZ management 109 (FIGS. 1, 1A) forexample, a TZ loader 119 (FIGS. 1, 1A), makes the corresponding TZlibrary 113 available, for example, by opening the files in the TZlibrary 113, or loading the TZ library data into computer memory.

Having established the desired TZ library format, at 230 the TZ nameretriever 115 (FIGS. 1, 1A) searches through the versions of TZIDversion 112 that are associated with the TZ library 113, in the searchorder established by the TZ version checker 117 (FIGS. 1, 1A), to findan entry matching the desired TZ name. A TZ name setting may beretrieved from a user or application customized profile, or may besupplied from the system default profile, in a manner similar to how aprofile setting for a TZ library is derived. As previously describedwith reference to FIG. 1B, the TZID version 112 may exist in the TZIDversion library 112 a as versioned updates to the TZ library 113. Thesearch order of the TZID versions 112 may be set along with other TZLrules of reconfiguration 111 (FIGS. 1, 1A), i.e., in the user,application, or default profile.

If, at 235, an entry matching the desired TZ name is found, the correctTZ rule for the desired geographical location is loaded at 260. However,if at 235, an entry matching the desired TZ name is not found within theselected TZ library 113 and all the TZID versions 112 have beenexhausted, if there is another TZID version 112 available to search, at240, the TZ loader 119 (FIGS. 1, 1A), opens the next TZ library 113 at245, and the search is performed on the TZID versions 112 within thisnew TZ library 113. However, if this is the last TZ library 113 and theTZ name still is not located, then at 250 a default TZID version 112 orTZ library 113, TZID version 112 pair or a default format, such as theUTC format, is set for the subsequent processing. At 260, the TZ rulefor the desired geographical location is loaded from the default settingat 260.

If, at 265, the TZ rule as selected at 260 indicates that DST isobserved, then at 270 the DST rule from the TZ rule is applied to derivelocal time, otherwise, at 275 local time is calculated from the normal,i.e., standard, TZ rule for the TZ name. Proper display of thenewly-derived local time depends upon applying a set of languageconventions that are consistent with the geographical location that isassociated with the TZ name. For example, some languages, such asEnglish, may be represented using standard American Standard Code forInformation Interchange (ASCII) encoding. However, languages such asChinese or Japanese require an extended language encoding usingmultibyte characters. Language conventions, also called locale settings,are a set of parameters that define the language, country, and localvariations for display of date and time, currency, rendering and layoutof text strings, for example. At 280, TZ management 109 (FIGS. 1, 1A)retrieves, either directly or by requesting such from the operatingsystem, or the applicable environment variables, particularly LANG.Unlike the time zone environment variables with respect to the TZL rulesof reconfiguration 111 (FIGS. 1-1B), the LANG environment variable is asystem-wide value. An individual user or application may override LANGwith variants of a local environment variable in the form of “LC_,” suchas LC_TIME for determining locale rules governing date and timeformatting and LC_MONETARY for formatting money values.

If at 285, a user or application has defined local overrides to the LANGenvironment variable, at 290, the derived local time is formatted usingthe local overrides. By default, however, at 295, the system-wide POSIXLANG setting is applied.

At 299, the derived local time is displayed using the desiredlocalization settings. However, the user may not approve of thedisplayed local time, for example, if the start and stop dates and timesare incorrect for DST. In that case, as described with reference to theTZ version checker 117 of FIGS. 1 and 1A, the user may optionally changeone or more selections in the request, such as, for example, therequested TZ library, a different TZID, or a different localizationsetting, and perform the search request again.

Referring now to FIG. 3, computing device 300 may include respectivesets of internal components 800 and external components 900 thattogether may provide an environment for a software application, such asa time zone (TZ) management system. Each of the sets of internalcomponents 800 includes one or more processors 820; one or morecomputer-readable RAMs 822; one or more computer-readable ROMs 824 onone or more buses 826; one or more operating systems 828; one or moresoftware applications (e.g., TZ management 829) executing the method200; and one or more computer-readable tangible storage devices 830. Theone or more operating systems 828 and time zone management modules 829are stored on one or more of the respective computer-readable tangiblestorage devices 830 for execution by one or more of the respectiveprocessors 820 via one or more of the respective RAMs 822 (whichtypically include cache memory). In the embodiment illustrated in FIG.3, each of the computer-readable tangible storage devices 830 is amagnetic disk storage device of an internal hard drive. Alternatively,each of the computer-readable tangible storage devices 830 is asemiconductor storage device such as ROM 824, EPROM, flash memory or anyother computer-readable tangible storage device that can store acomputer program and digital information.

Each set of internal components 800 also includes a R/W drive orinterface 832 to read from and write to one or more computer-readabletangible storage devices 936 such as a CD-ROM, DVD, SSD, memory stick,magnetic tape, magnetic disk, optical disk or semiconductor storagedevice.

Each set of internal components 800 may also include network adapters(or switch port cards) or interfaces 836 such as a TCP/IP adapter cards,wireless WI-FI interface cards, or 3G or 4G wireless interface cards orother wired or wireless communication links. The time management modules829, and operating system 828 that are associated with computing device300, can be downloaded to computing device 300 from an external computer(e.g., server) via a network (for example, the Internet, a local areanetwork, or other wide area network) and respective network adapters orinterfaces 836. From the network adapters (or switch port adapters) orinterfaces 836 and operating system 828 associated with computing device300 are loaded into the respective hard drive 830 and network adapter836. The network may comprise copper wires, optical fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers.

Each of the sets of external components 900 can include a computerdisplay monitor 920, a keyboard 930, and a computer mouse 934. Externalcomponents 900 can also include touch screens, virtual keyboards, touchpads, pointing devices, and other human interface devices. Each of thesets of internal components 800 also includes device drivers 840 tointerface to computer display monitor 920, keyboard 930 and computermouse 934. The device drivers 840, R/W drive or interface 832 andnetwork adapter or interface 836 comprise hardware and software (storedin storage device 830 and/or ROM 824).

Various embodiments of the invention may be implemented in a dataprocessing system suitable for storing and/or executing program codethat includes at least one processor coupled directly or indirectly tomemory elements through a system bus. The memory elements include, forinstance, local memory employed during actual execution of the programcode, bulk storage, and cache memory which provide temporary storage ofat least some program code in order to reduce the number of times codemust be retrieved from bulk storage during execution.

Input/Output or I/O devices (including, but not limited to, keyboards,displays, pointing devices, DASD, tape, CDs, DVDs, thumb drives andother memory media, etc.) can be coupled to the system either directlyor through intervening I/O controllers. Network adapters may also becoupled to the system to enable the data processing system to becomecoupled to other data processing systems or remote printers or storagedevices through intervening private or public networks. Modems, cablemodems, and Ethernet cards are just a few of the available types ofnetwork adapters.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions and the like can bemade without departing from the spirit of the disclosure, and these are,therefore, considered to be within the scope of the disclosure, asdefined in the following claims.

What is claimed is:
 1. A computer program product for retrieving localtime using a plurality of time zone (TZ) libraries comprising: acomputer readable storage medium readable by a processing circuit andstoring instructions for execution by the processing circuit forperforming a method comprising: receiving, by a TZ management componentof an operating system, a request for a local time setting of acomputer, wherein the request includes a preferred TZ library, apreferred TZ information data (TZID) version, a preferred TZ name, aplurality of TZ library rules of reconfiguration, and a TZ nameretrieval policy; searching each of a plurality of TZ libraries and eachof a plurality of TZID versions, wherein the plurality of TZ librariesand the plurality of TZID versions are integrated into the operatingsystem and are searched using a default TZ library pointer, beginningwith the preferred TZ library, in a user-defined pre-defined searchorder, for the preferred TZID version and the preferred TZ name, whereinthe default TZ library pointer is dynamically updated to point to acurrent library being searched; based on the searching returning thepreferred TZID version and the preferred TZ name, dynamically loading acorresponding TZ rule for formatting the local time of the computerwithout restarting the operating system or application; based on thesearching not returning the preferred TZID version and the preferred TZname, dynamically loading a default TZ rule, based on a setting of thedefault TZ library pointer without restarting the operating system orapplication; based on the TZ rule indicating that daylight savings time(DST) is observed, applying the DST rule from the TZ rule for derivingthe local time; and formatting the local time using a system-widelocalization rule or a user-defined localization rule.
 2. The computerprogram product of claim 1, wherein the plurality of TZ rules ofreconfiguration include: at least one pre-defined environment variable;a list for prioritizing an order in which to load the plurality of TZlibraries and the plurality of TZID versions; a list of operating systemdirectories and files used by the operating system to locate and loadthe plurality of TZ libraries and the plurality of TZID versions; andlogic for selecting and reconfiguring the search order of the pluralityof TZ libraries and the plurality of TZID versions.
 3. The computerprogram product of claim 1, further comprising: displaying a list ofavailable TZID versions from a TZ library; re-ordering the displayedlist of available TZID versions and the default TZ library pointer,based on user-defined input; updating the default TZ library pointer andthe TZ version checker with the re-ordered list of available TZIDversions; and utilizing automatically the re-ordered list of availableTZID versions without restarting the operating system and withoutrestarting an application.
 4. The computer program product of claim 1,wherein the TZID versions are at least one of: an ordered list; a linkedlist; one or more arrays; one or more tables; and a set of algorithms.5. The computer program product of claim 1, wherein the default TZlibrary pointer is set to a default TZ library and default TZID versionpair, based on a user-defined search order.
 6. The computer programproduct of claim 1, wherein the default TZ library pointer isautomatically reset to a new TZ library and a new TZID version pair,based on the TZ rules of reconfiguration dynamically changing the searchorder of the plurality of TZ libraries and the plurality of TZIDversions.